Rockmite Log 22/11/29 : Antennas, broken keyers, and SWR meters

Based on comments from the RSGB dipole antenna notes, I'm back to thinking I should try the 'radio in the middle' dipole configuration for the Rockmite. The page mentions that the coax leading to a dipole can pick up a noticeable amount of noise without a balun. I have a Rockmite board already wired up this way. The issues with the radio in the middle mode of operation are:

Biggest of all in this climate: moisture! I currently house the radio bare between the antenna wires. It's very, very foggy here on occasion. That, I suspect may also kill propagation though, so in its own way may not be an issue.
Obtaining the necessary length of CAT-5 wire to carry power, audio, and keyer signals
Tension relief for the antenna leads that hook directly into the board. (Especially important since the tree suspension system uses tree branches in conjunction with twine to support the antenna as close to horizontal as possible using increasing amounts of tension.

On a pragmatic note. The keyer—at the moment, it looks like it's the button itself—broke last night. So, I've got to setup a small soldering station this morning to make the whole thing better. A bit of a chore. It's that far left button (for dits) shown in the picture below.

OK! The key's fixed!

I setup a small soldering station in the house (we got a deal from Radio Shack during hte pandemic)

The bad button's on the left. I moved it to the unused right-hand button with under the board wiring this time.

The underboard wiring seems to have fixed the issue I had with the headphones 'singing' when they were near the keyer.

Before I move too much farther along with this, I need data on how well the current antenna operates. For example, do I need insulators between the antenna and the twine supporting it? One way to answer that question would be to look at the standing wave ratio of the antenna, (SWR), and for that I'll need a low-power SWR meter like this one from lloydm.net.

Operations:

Moving to the other side of the hill, (away from SF and towards the Southeast Bay), worked! No QSOs, but the RBN did pick up the station! Also! The higher antenna seemed to haved helped with signal strength into Canada. Note the 5 dB increase in signal to noise ratio!

The noise that was present when looking at town from the other tree setup is gone in this location.

Comments

Cool Math Tricks: Deriving the Divergence, (Del or Nabla) into New (Cylindrical) Coordinate Systems

Now available as a Kindle ebook for 99 cents ! Get a spiffy ebook, and fund more physics The following is a pretty lengthy procedure, but converting the divergence, (nabla, del) operator between coordinate systems comes up pretty often. While there are tables for converting between common coordinate systems , there seem to be fewer explanations of the procedure for deriving the conversion, so here goes! What do we actually want? To convert the Cartesian nabla to the nabla for another coordinate system, say… cylindrical coordinates. What we’ll need: 1. The Cartesian Nabla: 2. A set of equations relating the Cartesian coordinates to cylindrical coordinates: 3. A set of equations relating the Cartesian basis vectors to the basis vectors of the new coordinate system: How to do it: Use the chain rule for differentiation to convert the derivatives with respect to the Cartesian variables to derivatives with respect to the cylindrical variables. The chain ...

The Alcubierre Warp Drive Tophat Function and Open Science with Sage

I transferred yesterday's Mathematica file with the Alcubierre warp drive[2] line element and space curvature calculations to the +Sage Mathematical Software System today, (the files been added to the public repository [3]). If you haven't used Sage before, it's a Python based software package that's similar in functionality to Mathematica. Oh, and it' free. I also worked a little more on understanding the theory, but frankly, I made far more progress with the software than the theory. What follows will be a little more of the Alcubierre theory, plus, a cool Sage interactive demo of one of the Alcubierre functions[1], as well as a bit about my first experience with using Sage. Theory The theory is fun, but it's moving slowly. Here's the chalk board from this morning's discussion Alcubierre setup the derivation using something called the 3+1 formalism which means we consider space to be flat, (in this case), slices that are labelled ...

How Many Files Can You Add to a GPT Project? An Interview with GPT-5 on Limits, Context Engineering Tips, and Chats

Setting the scene: I’m tinkering with Project TouCans, knee-deep in radio logs, SQLite dumps, and Cesium code. Naturally, I’m wondering if shoving all this into one GPT Project is a recipe for brilliance… or for disaster. So I turn to Vril — you know, after Brainy from the Legion of Super-Heroes , because what else do you call your AI sidekick who always has the answers? Time to ask him straight up. [ As an aside, yes, GPT-5 has decided to sometimes call me Vail. I'm not sure why to be honest. Also, I asked Vril, er GPT-5, to write up our interview for me. Apparently, me asking it to 'Bro' up a few stories, just for fun, has convinced Vril that I use 'Like,' more than I actually might. ] Me (Vail): So Vril, how many files can I throw into a GPT Project before it just starts choking? Like, is there some magic number where the context window taps out and everything falls apart? GPT-5 (Vril): Great question. There’s no single hard file limit. What matters is ...

Copasetic Flow

Search This Blog